Fluid treating filter

ABSTRACT

An improved air filter including an expanded filamentous mat and a support frame in communication therewith extending along the perimeter of the mat, the expanded filamentous mat including a plurality of thickness wherein the filament density varies from thickness to thickness.

I United States Patent 11 1 1111 3,759,393 Tate et al. Sept. 18, 1973[54] FLUID TREATING FILTER 3,388,536 6/1968 Nash 55/492 3,460,321 8/1969Canzoneri 55/522 [751 lm'emors- 3"" 5cm", 3,526,557 9/1970 Taylor et al.156/167 both of Loulsvllle, y 3,690,852 9/1972 Smith et a1 55/485 [73]Assignee: American Air Filter Company, Inc., FOREIGN PATENTS ORAPPLICATIONS Lmllswlle, 1,097,917 1/1968 Great Britain 55 524 22 Filed:Aug 5 1971 1,105,306 3/1968 Great Britain 55/524 1 1 pp N04 1699318Primz zry Examiner-Brsmard Nozick Attorney-Charles G. Lamb et a1.

[52] US. Cl 210/491, 55/487, 55/514,

' 55/524, 55 527 ABSTRACT [51] Int. Cl B0ld 46/10 An improved air filterincluding an expanded filamen- [58] Field of Search tous mat and asupport frame in communication there- 55/485487, 492, 514, 524, 527;210/491 with extending along the perimeter of the mat, the expandedfilamentous mat including a plurality of thick- [56] References Citedness wherein the filament density varies from thickness UNITED STATESPATENTS to thickness- 2,l38,874 12/1938 Myers 55/D1G. 31

4 Claims, 2 Drawing Figures PAIEmEnsww 3.759.393

' INVENTOR flaw/1m 0 $617011 BACKGROUND OF THE INVENTION naces, and thelike, the air to be processed is usually passed through a filter toremove particles of dust and other foreign matter. For many years,filters utilizing fibrous material, such as fiberglas, as a filteringmedia, have been used for removing the undesirable particles within thescope of the present invention will occur to those skilled in the artupon reading the disclosure set from the air. These filters come in manysizes and shapes and are constructed by many different methods. One ofthe most common type of filters in use today is one in which the basiccore of loosely packed glass fibers bound together by a resinous coatingis confined between two closely perforated sheets of bright brass. Theperforated sheets are generally scrap from bottle plants and containclose. circular orifices placed as closely together as possible. Thecircular orifices account for nearly 90 percent of the total sheet area.The

fiberglas media and the two closely perforated sheets of bright brassare held together by an inwardly facing U- channel constructed offiberboard. The side pieces of fiberboard are either stapled together attheir ends to hold them intact with the perforated sheets or they areattached to the perforated sheets with an adhesive. Further, in somecases a narrowed metal strip is added to extend diagonally across eachbase of the perforated sheets to give extra strength.

SUMMARY OF THE INVENTION In the present invention, it is recognized thatit is desirable to provide a filter which is inexpensive, but yetdurable in present air filtering systems. Furthermore, it

isrecognized that his desirable to provide a filter which is easilyconstructed. Also, it is recognized that it is desirable to provide afilter having support means straightforward arrangement forthepreparation of an inherently structurally stable filter which may be utilized in furnaces, air conditioners, and the like. The present inventionfurther provides a fluid treating filter having support means includedtherein. 1

Various other features of the present invention will A 7 become obviousto those skilled in the art upon reading the disclosure set forthhereinafter. l

More particularly, the present invention providet a fluid treatingfilter comprising an expanded filam ntous mat and a support frame incommunicative relation therewith; the mat having a first and'a secondthickness, each thickness containing a plurality of filament layers, thefilaments being held in place by a binder; the concentration of thefilaments in the portion being relatively varied.

It is to be understood that the description of the examples of thepresent invention given hereinafter are not by way of limitation andvarious modifications forth hereinafter.

Referring to the drawings:

FIG. 1 is a perspective view of a filter of the present invention;

FIG. 2 is a reduced partially cut-away perspective view taken alonglines 2--2 of FIG. 1.

FIGS. 1 and 2 of the drawing illustrate one structure of a fluid filterof the present invention. A fluid filter I illustrated in the Figuresincludes a fibrous mat 6 having a first portion or thickness 2 and asecond portion or thickness 3. Fibrous mat 6 is of unitary construction,the filaments in portions 2 and 3 being similar but the concentration ofthe filaments being different in the two portions. In the example,portion 3 has a higher filament concentration than portion 2. Thedifference of the concentration in the portions will be discussedhereinafter.

Along the perimeter of the portion having the lesser concentration offilaments, portion 2 of the fibrous mat 6, is a metal frame 4, frame 4being held in communicative relation with a face of portion 2 by abinder. Binders which may be used for attaching frame 4 to the filterfibrous mat 6 include, for example, hide glues, bone glues, polyethyleneresins, polypropylene resins, ethylene vinyl acetate and the like.However, it is recognized that the frame may be sewn to the fibers orattached by other means withoutdeparting from the scope of the presentinvention. Furthermore, the frame 4 may be constructed of materialsother than metal, such as a plastic. 4

It has been found that in one preferred method, a liquid binder is addedto portion 2 along the perimeter that frame 4 is to be attached in anamount sufficient to extend into portion 3. In this method frame 4 ispressed firmly onto portion 2 but is also in contact with the binder inportion 3. Thus, frame 4 is actually attachedto portion 3 throughportion 2 and the rigidity of the support is enhanced.

Fibrous mat 6 is composed of two portions, portion 2 and portion 3wherein portion 3 is, as mentioned pre viously, of a filamentconcentration higher than in portion 2. It is to be understood thatportion 2 and portion 3, illustratedas being of unitary construction,may be of dissimilar materials and attached to each otherby bindingmeans. However, the preferred mat is of unitary construction with onepreferred method of making the unitarily constructed mat havingdifferent concentrations of filaments in each portion being described inUS. Pat. No. 3,526,557. Thispatent teaches that expanded filamentousmats are made by feeding fiberglas filaments from a filament feedermeans to a rotating drum, collecting the filaments on the rotating drumat a selected angle of lay relative to a selected axis on the drum toform a first portion of a mat, and spraying the portion with a bindersolution of a given viscosity. A second portion is then prepared byagain feeding filamentsfrom a filament feeder means to a rotating drum,collecting the filaments on the drum at a selected angle of lay relativeto a selected axis of the drum to form .a

of the thickness of the mat. The expanded mat is then heated to aselected temperature to decrease the viscosity of the binder on thatportion of the mat having the lower viscosity binder to permitreorientation of the filaments of the portion while the binder of theother portion remains in a relatively more viscous condition to restrictreorientation of filaments of that particular portion. A portion of themat having the lower viscosity binder is then compressed a selectedamount while the binder is in less viscous condition, and the softenedbinder is then hardened while that portion is in a compressed condition.The amount of compression done and the type of binder selected is sodetermined that the compressed portion is rigid enough to support thefibrous mat in an operating position.

One example of a binder that may be used within the present inventionfor holding the filaments in place in a selected portion is the reactionproduct of urea and formaldehyde in a solution having a preselectedsolids concentration wherein the ratio of urea to formaldehyde is 1.7parts by weight urea to 1.0 part by weight of formaldehyde. Thepreselected solids concentration will vary for each viscosity therebyenabling the same binder, but at different concentrations, to be used inthe differentportions of the mat.

In a fluid treating filter of the present invention, the filter isgenerally installed in a selected filter apparatus wherein the portionof the-filter having the lower concentration of filaments is theupstream or dirty air side and the portion having the higherconcentration of filaments is the downstream or clean air side. Further,generally the concentration of filaments in the downstream portion issufficient to support the filter in operating position. Thus, the metalframe support 4 attached to portion 2 in combination with the supportinherent in portion 3 makes for a filter having a balanced and uniformsupport throughout.

It will be realized that various changes may be made to the specificembodiments shown and described without departing from the principlesand spirit of the present invention.

Having thus described our invention, what is claimed 1. A fluid treatingfilter comprising an expanded filamentous mat and a support frame incommunicative relation therewith; said mat having first and secondfilament layers, the filaments of the layers being bonded by a binder,and the concentration of said filaments in said layers being different,said support frame being superposed the layer having the lowerconcentration of filaments and bonded to the layer having the higherconcentration of filaments with the layer having the lower concentrationof filaments being disposed therebetween and bonded to said supportframe, the support frame extending only adjacentlyalong the peripheraledge of said mat.

2. The fluid treating filter of claim 1 wherein the binder'in the firstportion and the binder in the second portion are of differentviscosities.

3. The fluid treating filter of claim 1 wherein the mat is of unitaryconstruction.

4. The fluid treating filter of claim 1 wherein the concentration offilaments in one of said portions is sufficient to support said filterin operating position.

1. A fluid treating filter comprising an expanded filamentous mat and asupport frame in communicative relation therewith; said mat having firstand second filament layers, the filaments of the layers being bonded bya binder, and the concentration of said filaments in said layers beingdifferent, said support frame being superposed the layer having thelower concentration of filaments and bonded to the layer having thehigher concentration of filaments with the layer having the lowerconcentration of filaments being disposed therebetween and bonded tosaid support frame, the support frame extending only adjacently alongthe peripheral edge of said mat.
 2. The fluid treating filter of claim 1wherein the binder in the first portion and the binder in the secondportion are of different viscosities.
 3. The fluid treating filter ofclaim 1 wherein the mat is of unitary construction.
 4. The fluidtreating filter of claim 1 wherein the concentration of filaments in oneof said portions is sufficient to support said filter in operatingposition.